Spirometer

ABSTRACT

A spirometer has a cabinet-like frame adapted to receive a deformable bag having one wall disposed against an abutting frame surface. A primary plate is hinged at its top on the frame to rest by gravity against an opposite wall of the bag. A valved inlet opening into the bag admits air to enlarge the bag. Movement of the enlarging bag swings the primary plate and moves an electrical transducer actuating an electrical meter and an electric light. An outlet valve moved by a solenoid controls air flow out of the bag. A secondary plate is hinged at its top to the frame to swing against and with the primary plate. An electric motor moves the secondary plate from a parked position against the primary plate to expel air from the bag. The outlet valve solenoid is timed to open the outlet valve accordingly. The motor moves the secondary plate away from the primary plate and back to the parked position, the outlet valve solenoid being simultaneously energized and the outlet valve closed.

United States Patent 1 I June 17, 1975 [73] Assignee: Searle Cardio-Pulmonary Systems Inc., Emeryville, Calif.

[22] Filed: Oct. 4, 1973 [21] Appl. No.: 403,467

[52] US. Cl 128/2.08; 346/72 [51] Int. Cl A61b 5/08 [58] Field of Search 128/2.08,2.07,26, 128/145.5145.8,202; 272/57 F; 346/72 [56] References Cited UNITED STATES PATENTS 1,781,735 11/1930 Scott 128/2.08

2,089,432 8/1937 Ryan l28/2.08 2,228,983 l/l941 Bloomheart... 128/2.08 3,082,761 3/1963 Engelder 128/2.08 X 3,154,068 10/1964 Reinert et al. l28/2.08 3,304,939 2/1967 Manley 128/145.7 3,319,624 5/1967 Arp et a1 128/2.08 3,363,260 1/1968 Garbe 128/2.08 3,420,225 1/1969 Holden et a1. l28/2.08 3,757,776 9/1973 Bauman l28/l45.6 3,808,706 5/1974 Mosely et a1. 128/2.08

FOREIGN PATENTS OR APPLICATIONS 599,758 5/1928 Germany 128/2.08

OTHER PUBLICATIONS Gisser, et al., A Refined Bag-BoxSpirometer, J.

Assn. for Adv. of Med. Inst., Vol. 6, No. 2, Man-Apr. 72.

Primary ExaminerRichard A. Gaudet Assistant ExaminerLee S. Cohen Attorney, Agent, or Firm-Lothrop & West [57] ABSTRACT A spirometer has a cabinet-like frame adapted to receive a deformable bag having one wall disposed against an abutting frame surface. A primary plate is hinged at its top on the frame to rest by gravity against an opposite wall of the bag. A valved inlet opening into the bag admits air to enlarge the bag. Movement of the enlarging bag swings the primary plate and moves an electrical transducer actuating an electrical meter and an electric light. An outlet valve moved by a solenoid controls air flow out of the bag. A secondary plate is hinged at its top to the frame to swing against and with the primary plate. An electric motor moves the secondary plate from a parked position against the primary plate to expel air from the bag. The outlet valve solenoid is timed to open the outlet valve accordingly. The motor moves the secondary plate away from the primary plate and back to the parked position, the outlet valve solenoid being simultaneously energized and the outlet valve closed.

9 Claims, 5 Drawing Figures SHEET PATENTEDJUN 17 m5 FIG..1

FlG 2 SHEET FIG- 5 SPIROMETER In the treatment of some patients a respirator must be utilized to produce programmed breathing. It is then of interest to get an indication or measurement of the air volume breathed by the patient during each breath. The measurement can also include a showing of variations in breathing.

It is therefore an object of the invention to provide a spirometer which is readily adaptable to use with a respirator or can be used by itself to measure the volume of a patients breath and to indicate the nature of his breathing.

Another object of his invention is to provide a spirometer in which patient effort is extremely small in i order to distort as little as possible accurate indications of his breathing.

A further object of the invention is to provide a spirometer in which portions of the apparatus coming in contact with the patients breath are easily and cheaply replaceable.

Another object of the invention is to provide a spirometer in which the functioning of some of the apparatus is accomplished by electrical power rather than by patient power.

Another object of the invention is in general to provide an improved spirometer.

Other objects, together with the foregoing, are attained in the embodiment of the invention described in the accompanying description and illustrated in the accompanying drawings, in which:

FIG. 1 is an elevational view of a spirometer constructed in accordance with the invention, one of the side walls being removed to show the interior arrangement;

FIG. 2 is a cross-section, the plane of which is indicated by the line 22 of FIG. 1;

FIG. 3 is a top plan view of the spirometer;

FIG. 4 is a detail showing microswitches and their actuators; and

FIG. 5 is an enlarged detail showing the outlet portion of the device.

In an exemplary form of spirometer the device can be used alone but it is primarily useful in connection with a respirator of the sort shown in the copending application of Buck, Kitrilakis and Robinson Ser. No. 354,673 filed Apr. 26, 1973.

For use with such an apparatus or otherwise, there is generally afforded a breathing tube 6 extending from the patient and carrying his exhalation through a check valve 7 into an inlet tube 8 forming part of a collapsible bag 9 usually fabricated of heat-sealed plastic sheets in an inexpensive fashion so that each use of the spirometer may be with an individual bag. The bag in side elevation, when extended, is of triangular configuration and in front elevation is generally rectangular and is provided with a downwardly extending or depending portion 10 at the bottom receiving a tub 11 extending to one side and having a cutaway portion 12 to communicate freely with the inside of the bag.

The spirometer includes a frame 21 in the form of a cabinet having side walls 22 and 23 and generally enclosed otherwise but with the wall 22 removable or hinged to swing out of the way so that a bag 9 can be put into position with one of the bag walls in abutment with the wall 22 of the cabinet frame. When so positioned the depending portion 10 of the bag extends downwardly and the tube 11 is at the bottom of the frame cabinet. The connection 8 extends through an appropriate aperture in the cabinet.

Designed to rest against the opposite wall of the bag 9 is a primary plate 24 of almost the same extent as the bag wall and mounted at its top on a hinge rod 26 secured to the frame to lie on a generally horizontal axis close to the wall 22 so that when unrestrained and under the force of gravity alone the primary plate 24 depends in a vertical position.

In a similar fashion there is provided a secondary plate 27 of nearly the same height as the primary plate but of substantially lesser width, yet centered with respect thereto, and itself mounted to swing about a generally horizontal axis by means of a hinge mounting 28 which is preferably parallel to and very close to the hinge mounting 26. In one variation the two plates 24 and 27 can be hinged to swing from and depend from the same axis.

Position of the primary plate 24 is utilized as an indi-' cation of the volumetric content of the bag and so as an indication of the volume of the contained breath. Bag position or movement can be observed directly but preferably are specially indicated. In the present instance there is mounted on the frame an electrical transducer 31 of any convenient type secured in position by a bracket 32 and having a movable element 33 joined by a flexible wire or string 34 to a bracket 36 on the primary plate 24. The string 34 passes around a pulley 37 carried by a bracket 38 on the frame so that the movement of the member 33 is rectilinear.

The transducer 31 is electrically connected by appropriate means to an indicator or display meter 41 mounted on the inclined cover plate 42 of the cabinet frame. In parallel with the meter 41 there is also mounted on the top panel 42 an electric light 43 joined in the same circuitry.

In operation, as the primary plate 24 moves or swings to and fro under the propelling impetus of the expanding bag and then back under the influence of gravity when the bag contracts, the transducer 31 provides a comparable movement of the needle of the meter 41 and also provides a variable light output or glow from the light 43. By observing either the meter or the light or both of them, an observer may gain a correct indication of the exhalation quantity and cycle of the patient.

Also mounted on the panel 42 is a manually adjustable controller 46 which is settable to different positions and is included in the electric circuitry to the transducer 31 in such a way as to sound an alarm in the event the tidal volume or exhalation quantity of the patient varies from a set value. There is also provided a control 47 on the panel which is effective to accumulate successive deficits in the tidal volume according to its setting and then to give an alarm.

In order that the bag 9 can be expanded during exhalation and then can be restored to its initial, collapsed condition, there is provided in addition to the inlet valve 7 an appropriate outlet valving means. In the present instance this includes a valve plate 51 mounted for reciprocation on the frame in a position opposite the depending portion 10 of the bag. The valve plate is movable between a first position forcing the walls of the bag tightly together and against the frame wall 22 so as to shut off flow and a second position in which the valve plate 51 is retracted and allows the bag, especially the depending portion thereof, to deform and open under the pressure of outflowing air.

The plate 51 is mechanically moved. It is impelled to I move by a solenoid 52 mounted on the frame and by an opposing spring 53, their motion being communicated through a bell crank 54 pivoted on the frame and engaging the solenoid stern and the valve plate 51. Preferably, when the spring 53 alone is effective the valve plate 51 is retracted and the bag is open to discharge, whereas when the solenoid 52 is energized the spring 53 is overcome and the plate 51 is moved toward the cabinet wall 22 and pinches off and closes the bag outlet. The valve 51 can sometimes be replaced by a pressure differential responsive valve opened by exhaust pressure from the bag 9. Also the primary plate 24 can be made heavy enough to act solely by gravity to collapse the bag with enough force to open an unbalanced outlet valve. However, it is much preferred to relieve the patient of the labor of having to lift a relatively heavy primary plate 24 by the pressure of his exhalation.

In order to relieve the patient of as much'work as possible the primary plate is made very light and the secondary plate 27 is mechanically actuated as is the outlet valve plate 51. For that reason there is mounted within the cabinet and on the frame an electric motor 61 supplied with power through certain auxiliary devices, such as a transformer 62, and with attendant starting mechanisms 63. The motor is effective when energized to operate through a gear reduction unit 64 slowly to rotate a rotor shaft 66. This shaft caries a drive disc 67. A crank pin 68 on the disc is connected by a pitman 69 and a wrist pin 71 to a bracket 72 on the secondary plate 27.

As the energized motor 61 rotates the disc 67 the plate 27 is swung or reciprocated. This reciprocatory motion is carefully controlled. Preferably the shaft 66 has a cam lobe 73 in position to actuate a microswitch 74. When so actuated the switch opens the circuit to the motor 61 and precludes rotation of the motor except and unless the motor circuit is otherwise closed. Such closure can be accomplished either by a manual push button 76 operating through a circuit 77 when the spirometer is used as an individual unit, or can be actuated by operation of a respirator exhalation valve 78 of the sort disclosed in the above-mentioned copending application.

The valve 78 is effective to close the circuit 77 and energize the motor 61 at the very end of the patients exhalation cycle or at the immediate beginning of the patients inhalation cycle. When the motor 61 is thus started the shaft 66 begins to turn, shifting the lobe 73 and thus permitting the microswitch 74 to close and continue the energization of the circuit even though the circuit 77 may by then be open. The discharge cycle occurs after the bag 9 has been filled by the patient as far as he can. The bag may be in a maximum full position with the primary plate 24 lifted into abutment with the secondary plate 27, or the bag may be only partly filled with the primary plate 24 in some intermediate location. In any event, as the secondary plate 27 is moved by the pitman 69 toward the cabinet wall 22, the secondary plate contacts the primary plate 24 and the force of the motor is then used to compact the bag 9.

After the rotor disc 67 has turned a half turn from its starting position, the secondary plate 27 has restored the primary plate 24 to its maximum collapsed position in almost immediate juxtaposition with the wall 22 and with the bag 9 fully discharged. The primary plate is left I there as the rotor disc 67 continues its rotation, since the circuit is still energized, and returns toward its initial position. ,As it arrives at the initial position, the cam lobe 73 again opens the microswitch 74, interrupts the circuit and causes the motor to stop the secondary plate in its full-cycle, fully retracted position, ready for a subsequent operation.

During the foregoing bag expulsion operation, it is necessary that the valve plate 51 be retracted to permit escape of the gas. For that reason, the drive disc 67 is contoured to provide a cam rim 81 (see FIG. 4) operating against a second microswitch 82 in circuit with the solenoid 52. Thus, as soon as the motor 61 is energized and starts the rotor disc 67 to turn (in a clockwise direction in FIG. 2), the cam rim 81 permits the microswitch 82 to open and de-energize the solenoid 52, so that the spring 53 immediately retracts the valve plate 51 to open the bag discharge. Then when the bag has been collapsed and the rotor has returned to its fullcycle position, the cam rim 81 again energizes the solenoid 52 so that the valve plate 51 is translated to close the bag outlet.

By this means there is afforded a spirometer in which the patients effort in exhaling is required to do little more work than simply to expand the flexible plastic bag 9 and to lift very slightly the relatively light primary plate 24, the work of expelling the expired air from the bag 9 being accomplished by electric power. During the spirometer operation the meter and light indicate the nature of the breathing effort during the exhalation cycle and the amount or the volume of expelled breath.

After protracted use, there is often some condensate or deposit on the inside of the bag 9, which drains by gravity when the valve plate 51 is retracted during discharge. Drainage is into the tube 11, from which it can be carried away from the machine with the expired breath. At the conclusion of one use of the spirometer, the cabinet is readily opened and the used bag 9 is withdrawn and discarded and is replaced by a new, sterile bag for subsequent use, the connections to the conduit 6 and to the tube 11 being readily made.

In this way it is easy to ensure that the patients breath is entirely confined to the bag and its connections and is isolated from the remaining parts of the device. The bag and its appurtenances are cheap enough and easily enough handled so that each user may have an individual bag disposed of after his use to maintain clean conditions.

What is claimed is:

1. In a spirometer, having a frame having an abutting surface adapted to receive an air bag thereagainst; a primary plate; means for supporting said primary plate on said frame for swinging movement about a superior, horizontal axis parallel to said surface and so positioned that said primary plate is gravity urged to a position adjacent said abutting surface, the improvement comprising: means for indicating the position of said primary plate relative to said frame; a secondary plate;

means supporting said secondary plate on said frame for swinging movement about substantially the same superior, horizontal axis; and means on said frame for holding said secondary plate away from saidlprimary plate and for swinging said secondary plate against said primary plate and forcibly swinging said primary and secondary plates as a unit toward said abutting surface.

2. A device as in claim 1 in which a deformable bag is between said abutting surface and said primary plate and has a portion depending below said primary plate provided with an air outlet, a valve plate, and means for mounting said valve plate on said frame for movement between a first position clamping saidportion against said frame and a second position free of said portion.

3. A device as in claim 2 including electrical means for moving said valve plate.

4. A device as in claim 3 including means forengaging said moving means in time with operation of said holding and swinging means.

5. A device as in claim 1 in which said holding and swinging means includes an electric motor.

6. A device as in claim 5 in which said holding and swinging means includes a rotor driven by said motor, and a pitman connecting said rotor and said secondary plate.

7. In a spirometer, having a frame establishing a stationary surface adapted to receive an air bag there-' against, a primary plate, means mounting said primary plate on said frame for free swinging movement toward and from said stationary surface in a predetermined path, the improvement comprising: means for indicating the position of the primary plate relative to said frame; a secondary plate, means mounting said secondary plate on said frame for swinging movement relative to said stationary surface in said predetermined path, and means for swinging said secondary plate in said predetermined path and into and away from abutment with said primary plate. I

8. A spirometer as in claim 7 including a deformable bag disposed between and in contact with said stationary surface and said primary plate.

9. A spirometer as in claim 8 including an air inlet to said bag and an air outlet from said bag. 

1. In a spirometer, having a frame having an abutting surface adapted to receive an air bag thereagainst; a primary plate; means for supporting said primary plate on said frame for swinging movement about a superior, horizontal axis parallel to said surface and so positioned that said primary plate is gravity urged to a position adjacent said abutting surface; the improvement comprising: means for indicating the position of said primary plate relative to said frame; a secondary plate; means supporting said secondary plate on said frame for swinging movement about substantially the same superior, horizontal axis; and means on said frame for holding said secondary plate away from said primary plate and for swinging said secondary plate against said primary plate and forcibly swinging said primary and secondary plates as a unit toward said abutting surface.
 2. A device as in claim 1 in which a deformable bag is between said abutting surface and said primary plate and has a portion depending below said primary plate provided with an air outlet, a valve plate, and means for mounting said valve plate on said frame for movement between a first position clamping said portion against said frame and a second Position free of said portion.
 3. A device as in claim 2 including electrical means for moving said valve plate.
 4. A device as in claim 3 including means for engaging said moving means in time with operation of said holding and swinging means.
 5. A device as in claim 1 in which said holding and swinging means includes an electric motor.
 6. A device as in claim 5 in which said holding and swinging means includes a rotor driven by said motor, and a pitman connecting said rotor and said secondary plate.
 7. In a spirometer, having a frame establishing a stationary surface adapted to receive an air bag thereagainst, a primary plate, means mounting said primary plate on said frame for free swinging movement toward and from said stationary surface in a predetermined path, the improvement comprising: means for indicating the position of the primary plate relative to said frame; a secondary plate, means mounting said secondary plate on said frame for swinging movement relative to said stationary surface in said predetermined path, and means for swinging said secondary plate in said predetermined path and into and away from abutment with said primary plate.
 8. A spirometer as in claim 7 including a deformable bag disposed between and in contact with said stationary surface and said primary plate.
 9. A spirometer as in claim 8 including an air inlet to said bag and an air outlet from said bag. 